Bumper arrangements having hollow spaces therein are known. For example, Berry U.S. Pat. No. 1,486,222 discloses a tubular bumper adapted to carry an emergency supply of fuel.
Postel U.S. Pat. No. 1,784,387 discloses a rubber bumper tube containing brake fluid and adapted to communicate same to actuate the brake drums in the event of an impact shock against the bumper tube.
Flamm U.S. Pat. No. 2,866,510 discloses a dual casting bumper arrangement for a tractor, with one casting containing a supply of hydraulic fluid, with a suction line leading therefrom to a pump assembly mounted in the second casting.
Bowman U.S. Pat. No. 2,993,721 discloses a rear bumper for a light truck formed of plates welded together to form outer box-like walls and inner walls separating aligned segments. Openings are formed through the inner walls, and a capped filler opening is mounted in an upper wall and a drain plug in a lower wall for containing water as ballast when the truck is empty.
Reich II U.S. Pat. No. 4,487,446 discloses a bumper having a hollow chamber in which compressed air is stored for inflating the tires of off-road vehicles.
Prochaska et al U.S. Pat. No. 4,525,005 discloses a bumper including two box shaped bars made of fiber-reinforced material and either bonded together or connected by an intermediate steel securing plate.
Baravalle U.S. Pat. No. 4,567,955 discloses a front bumper formed of a molded plastics material and having a front section of an air conveyor formed integrally therewith and secured to a fixed section intermediate the front section and the radiator, such that, in the event of a minor frontal collision, once the bumper returns to its initial position, the intermediate section is also returned to restore the effectiveness of the radiator.
DiGiusto U.S. Pat. No. 4,653,788 discloses a hollow front bumper having a front inlet aperture acting as an air intake, and two rear apertures defined by nozzles arranged to direct respective air flows toward the front wheel brakes, along with a rear tubular appendage acting as a duct for conveying an air flow toward the radiator.
Tritton U.S. Pat. No. 4,902,059 discloses upper and lower steel tubular bumper members, interconnected at their respective end portions by fluid passage spacers, such that engine coolant flows into and through one tubular member and through and out of the other.
Plastics Engineering, December 1992, pages 21-24, in an article entitled "Blow Molded Vehicle Bumper Beams," describes producing bumper box beams in one step.